The invention relates to an apparatus for the production of cushions with back-foamed covers, especially car seat cushions, broadly consisting of a mold with a mix head arranged on it. A fixing device may be placed above the lower half of the mold, to which at least one pressing element (pressure pad, shaping machine ram) with a pressing edge for pressing the cover material section is arranged.
As a rule, a so-called vacuum mold tool is used in devices of this kind, where the cover material is drawn into the mold by means of a vacuum. If necessary, the sliding of the cover material is controlled by means of a tenter which presses the cover material onto the rim surrounding the mold cavity. In addition, a so-called counter-die may be used which presses the cover material into the cavity in order to fit it more closely to the contour (see, e.g. German Offenlegungsschrift No. 27 46 686).
Even with a combination of several or of all of these aids, difficulties arise in completely laying down the cover at critical points (such as, for example, fins and corners, upon the sides of the mold cavity). As the upper half of the mold presses on the projecting rim of the cover material during back-foaming, the resulting foam pressure can no longer tighten the cover material and cannot lay the cover material completely against the side of the cavity. Incompletely formed cushions are of no use. The use of rollers as pressing elements has already been attempted. This fails at all places where the side of the form hollow is contoured because rollers of rigid material are not flexible and rollers of softer material (such as rubber or foamed material) no longer manage to roll-off, because of strong flexing.
The object of the present invention is to improve the pressing edges of the pressing elements in devices of the kind mentioned to the extent that the faultless laying of the cover material against the side of the mold cavity is possible even at particularly critical places, such as fins and corners .